1. Field of the Invention.
This invention relates a MacPherson strut upper mounts.
2. Description of the Prior Art
MacPherson strut suspensions offer a great advantage in the fact that a shock absorber doubles as a upper arm which helps in locating the wheel position of the motor vehicle. However, the fact that the shock absorber doubles as a strut consequentially means that the strut must be securly mounted onto the motor vehicle body. Most commonly the top end of the piston rod is mounted to the fender well or other structurally sound part of the body.
Due to the secure mounting of the piston rod to the vehicle body, vibrations from the wheel are transmitted through the MacPherson strut to the vehicle body. To eliminate such undesirable vibrations in the vehicle body it is necessary to mount the top end of the strut to the body simultaneously in a secure manner while isolating any vibrations that may transmit up through the strut. Known upper mounts have used elastomeric isolators to isolate the piston rod from the vehicle body. U.S. Pat. No. 3,279,782 issued to Schick on Oct. 18, 1966 discloses a onion shaped rubber mount which is secured within a casing bolted onto the vehicle body. U.S. Pat. No. 3,482,829 issued to Kidby on Dec. 9, 1969, U.S. Pat. No. 3,589,701 issued to Gee on June 29, 1971 and U.S. Pat. No. 4,105,222 issued to Buchwald on Aug. 8, 1978 disclose annular elastomeric pads mounting the top end of the piston rod to the vehicle body.
It is also known to have a jounce bumper mounted above the MacPherson strut cylinder about the piston rod and below the elastomeric isolator which secures the piston rod to the body. Examples of two such devices are disclosed in U.S. Pat. No. 3,346,272 issued to Smith on Oct. 10, 1967, U.S. Pat. No. 4,042,259 issued to Fiedler et al on Aug. 16, 1977 and U.S. Pat. No. 3,941,401 issued to Allison on Mar. 2, 1976.
In addition, it is also known to isolate vibrations of the MacPherson strut from the vehicle body by the use of an isolator which is situated above and below a vehicle mounting plate. One such device is disclosed in U.S. Pat. No. 3,573,880 issued to Sakai on Apr. 6, 1971.
Due to refinements in the tuned ride of motor vehicles, and the use of MacPherson struts in these motor vehicles, it is desirable to isolate most vibrations transmitted through the MacPherson strut while maintaining the strut as a precise positioning control arm. It is also desirable to have an upper mount which can be easily tuned for a specific model.